kernel/rcu/rcutorture.c

   1 /*
   2  * Read-Copy Update module-based torture test facility
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, you can access it online at
  16  * http://www.gnu.org/licenses/gpl-2.0.html.
  17  *
  18  * Copyright (C) IBM Corporation, 2005, 2006
  19  *
  20  * Authors: Paul E. McKenney <paulmck@us.ibm.com>
  21  *        Josh Triplett <josh@joshtriplett.org>
  22  *
  23  * See also:  Documentation/RCU/torture.txt
  24  */
  25 #include <linux/types.h>
  26 #include <linux/kernel.h>
  27 #include <linux/init.h>
  28 #include <linux/module.h>
  29 #include <linux/kthread.h>
  30 #include <linux/err.h>
  31 #include <linux/spinlock.h>
  32 #include <linux/smp.h>
  33 #include <linux/rcupdate.h>
  34 #include <linux/interrupt.h>
  35 #include <linux/sched/signal.h>
  36 #include <uapi/linux/sched/types.h>
  37 #include <linux/atomic.h>
  38 #include <linux/bitops.h>
  39 #include <linux/completion.h>
  40 #include <linux/moduleparam.h>
  41 #include <linux/percpu.h>
  42 #include <linux/notifier.h>
  43 #include <linux/reboot.h>
  44 #include <linux/freezer.h>
  45 #include <linux/cpu.h>
  46 #include <linux/delay.h>
  47 #include <linux/stat.h>
  48 #include <linux/srcu.h>
  49 #include <linux/slab.h>
  50 #include <linux/trace_clock.h>
  51 #include <asm/byteorder.h>
  52 #include <linux/torture.h>
  53 #include <linux/vmalloc.h>
  54 #include <linux/sched/debug.h>
  55
  56 #include "rcu.h"
  57
  58 MODULE_LICENSE("GPL");
  59 MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and Josh Triplett <josh@joshtriplett.org>");
  60
  61
  62 torture_param(int, cbflood_inter_holdoff, HZ,
  63               "Holdoff between floods (jiffies)");
  64 torture_param(int, cbflood_intra_holdoff, 1,
  65               "Holdoff between bursts (jiffies)");
  66 torture_param(int, cbflood_n_burst, 3, "# bursts in flood, zero to disable");
  67 torture_param(int, cbflood_n_per_burst, 20000,
  68               "# callbacks per burst in flood");
  69 torture_param(int, fqs_duration, 0,
  70               "Duration of fqs bursts (us), 0 to disable");
  71 torture_param(int, fqs_holdoff, 0, "Holdoff time within fqs bursts (us)");
  72 torture_param(int, fqs_stutter, 3, "Wait time between fqs bursts (s)");
  73 torture_param(bool, gp_cond, false, "Use conditional/async GP wait primitives");
  74 torture_param(bool, gp_exp, false, "Use expedited GP wait primitives");
  75 torture_param(bool, gp_normal, false,
  76              "Use normal (non-expedited) GP wait primitives");
  77 torture_param(bool, gp_sync, false, "Use synchronous GP wait primitives");
  78 torture_param(int, irqreader, 1, "Allow RCU readers from irq handlers");
  79 torture_param(int, n_barrier_cbs, 0,
  80              "# of callbacks/kthreads for barrier testing");
  81 torture_param(int, nfakewriters, 4, "Number of RCU fake writer threads");
  82 torture_param(int, nreaders, -1, "Number of RCU reader threads");
  83 torture_param(int, object_debug, 0,
  84              "Enable debug-object double call_rcu() testing");
  85 torture_param(int, onoff_holdoff, 0, "Time after boot before CPU hotplugs (s)");
  86 torture_param(int, onoff_interval, 0,
  87              "Time between CPU hotplugs (s), 0=disable");
  88 torture_param(int, shuffle_interval, 3, "Number of seconds between shuffles");
  89 torture_param(int, shutdown_secs, 0, "Shutdown time (s), <= zero to disable.");
  90 torture_param(int, stall_cpu, 0, "Stall duration (s), zero to disable.");
  91 torture_param(int, stall_cpu_holdoff, 10,
  92              "Time to wait before starting stall (s).");
  93 torture_param(int, stall_cpu_irqsoff, 0, "Disable interrupts while stalling.");
  94 torture_param(int, stat_interval, 60,
  95              "Number of seconds between stats printk()s");
  96 torture_param(int, stutter, 5, "Number of seconds to run/halt test");
  97 torture_param(int, test_boost, 1, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
  98 torture_param(int, test_boost_duration, 4,
  99              "Duration of each boost test, seconds.");
 100 torture_param(int, test_boost_interval, 7,
 101              "Interval between boost tests, seconds.");
 102 torture_param(bool, test_no_idle_hz, true,
 103              "Test support for tickless idle CPUs");
 104 torture_param(bool, verbose, true,
 105              "Enable verbose debugging printk()s");
 106
 107 static char *torture_type = "rcu";
 108 module_param(torture_type, charp, 0444);
 109 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, ...)");
 110
 111 static int nrealreaders;
 112 static int ncbflooders;
 113 static struct task_struct *writer_task;
 114 static struct task_struct **fakewriter_tasks;
 115 static struct task_struct **reader_tasks;
 116 static struct task_struct *stats_task;
 117 static struct task_struct **cbflood_task;
 118 static struct task_struct *fqs_task;
 119 static struct task_struct *boost_tasks[NR_CPUS];
 120 static struct task_struct *stall_task;
 121 static struct task_struct **barrier_cbs_tasks;
 122 static struct task_struct *barrier_task;
 123
 124 #define RCU_TORTURE_PIPE_LEN 10
 125
 126 struct rcu_torture {
 127         struct rcu_head rtort_rcu;
 128         int rtort_pipe_count;
 129         struct list_head rtort_free;
 130         int rtort_mbtest;
 131 };
 132
 133 static LIST_HEAD(rcu_torture_freelist);
 134 static struct rcu_torture __rcu *rcu_torture_current;
 135 static unsigned long rcu_torture_current_version;
 136 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 137 static DEFINE_SPINLOCK(rcu_torture_lock);
 138 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count);
 139 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch);
 140 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 141 static atomic_t n_rcu_torture_alloc;
 142 static atomic_t n_rcu_torture_alloc_fail;
 143 static atomic_t n_rcu_torture_free;
 144 static atomic_t n_rcu_torture_mberror;
 145 static atomic_t n_rcu_torture_error;
 146 static long n_rcu_torture_barrier_error;
 147 static long n_rcu_torture_boost_ktrerror;
 148 static long n_rcu_torture_boost_rterror;
 149 static long n_rcu_torture_boost_failure;
 150 static long n_rcu_torture_boosts;
 151 static long n_rcu_torture_timers;
 152 static long n_barrier_attempts;
 153 static long n_barrier_successes;
 154 static atomic_long_t n_cbfloods;
 155 static struct list_head rcu_torture_removed;
 156
 157 static int rcu_torture_writer_state;
 158 #define RTWS_FIXED_DELAY        0
 159 #define RTWS_DELAY              1
 160 #define RTWS_REPLACE            2
 161 #define RTWS_DEF_FREE           3
 162 #define RTWS_EXP_SYNC           4
 163 #define RTWS_COND_GET           5
 164 #define RTWS_COND_SYNC          6
 165 #define RTWS_SYNC               7
 166 #define RTWS_STUTTER            8
 167 #define RTWS_STOPPING           9
 168 static const char * const rcu_torture_writer_state_names[] = {
 169         "RTWS_FIXED_DELAY",
 170         "RTWS_DELAY",
 171         "RTWS_REPLACE",
 172         "RTWS_DEF_FREE",
 173         "RTWS_EXP_SYNC",
 174         "RTWS_COND_GET",
 175         "RTWS_COND_SYNC",
 176         "RTWS_SYNC",
 177         "RTWS_STUTTER",
 178         "RTWS_STOPPING",
 179 };
 180
 181 static const char *rcu_torture_writer_state_getname(void)
 182 {
 183         unsigned int i = READ_ONCE(rcu_torture_writer_state);
 184
 185         if (i >= ARRAY_SIZE(rcu_torture_writer_state_names))
 186                 return "???";
 187         return rcu_torture_writer_state_names[i];
 188 }
 189
 190 #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU)
 191 #define rcu_can_boost() 1
 192 #else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 193 #define rcu_can_boost() 0
 194 #endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 195
 196 #ifdef CONFIG_RCU_TRACE
 197 static u64 notrace rcu_trace_clock_local(void)
 198 {
 199         u64 ts = trace_clock_local();
 200
 201         (void)do_div(ts, NSEC_PER_USEC);
 202         return ts;
 203 }
 204 #else /* #ifdef CONFIG_RCU_TRACE */
 205 static u64 notrace rcu_trace_clock_local(void)
 206 {
 207         return 0ULL;
 208 }
 209 #endif /* #else #ifdef CONFIG_RCU_TRACE */
 210
 211 static unsigned long boost_starttime;   /* jiffies of next boost test start. */
 212 static DEFINE_MUTEX(boost_mutex);       /* protect setting boost_starttime */
 213                                         /*  and boost task create/destroy. */
 214 static atomic_t barrier_cbs_count;      /* Barrier callbacks registered. */
 215 static bool barrier_phase;              /* Test phase. */
 216 static atomic_t barrier_cbs_invoked;    /* Barrier callbacks invoked. */
 217 static wait_queue_head_t *barrier_cbs_wq; /* Coordinate barrier testing. */
 218 static DECLARE_WAIT_QUEUE_HEAD(barrier_wq);
 219
 220 /*
 221  * Allocate an element from the rcu_tortures pool.
 222  */
 223 static struct rcu_torture *
 224 rcu_torture_alloc(void)
 225 {
 226         struct list_head *p;
 227
 228         spin_lock_bh(&rcu_torture_lock);
 229         if (list_empty(&rcu_torture_freelist)) {
 230                 atomic_inc(&n_rcu_torture_alloc_fail);
 231                 spin_unlock_bh(&rcu_torture_lock);
 232                 return NULL;
 233         }
 234         atomic_inc(&n_rcu_torture_alloc);
 235         p = rcu_torture_freelist.next;
 236         list_del_init(p);
 237         spin_unlock_bh(&rcu_torture_lock);
 238         return container_of(p, struct rcu_torture, rtort_free);
 239 }
 240
 241 /*
 242  * Free an element to the rcu_tortures pool.
 243  */
 244 static void
 245 rcu_torture_free(struct rcu_torture *p)
 246 {
 247         atomic_inc(&n_rcu_torture_free);
 248         spin_lock_bh(&rcu_torture_lock);
 249         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 250         spin_unlock_bh(&rcu_torture_lock);
 251 }
 252
 253 /*
 254  * Operations vector for selecting different types of tests.
 255  */
 256
 257 struct rcu_torture_ops {
 258         int ttype;
 259         void (*init)(void);
 260         void (*cleanup)(void);
 261         int (*readlock)(void);
 262         void (*read_delay)(struct torture_random_state *rrsp);
 263         void (*readunlock)(int idx);
 264         unsigned long (*started)(void);
 265         unsigned long (*completed)(void);
 266         void (*deferred_free)(struct rcu_torture *p);
 267         void (*sync)(void);
 268         void (*exp_sync)(void);
 269         unsigned long (*get_state)(void);
 270         void (*cond_sync)(unsigned long oldstate);
 271         call_rcu_func_t call;
 272         void (*cb_barrier)(void);
 273         void (*fqs)(void);
 274         void (*stats)(void);
 275         int irq_capable;
 276         int can_boost;
 277         const char *name;
 278 };
 279
 280 static struct rcu_torture_ops *cur_ops;
 281
 282 /*
 283  * Definitions for rcu torture testing.
 284  */
 285
 286 static int rcu_torture_read_lock(void) __acquires(RCU)
 287 {
 288         rcu_read_lock();
 289         return 0;
 290 }
 291
 292 static void rcu_read_delay(struct torture_random_state *rrsp)
 293 {
 294         unsigned long started;
 295         unsigned long completed;
 296         const unsigned long shortdelay_us = 200;
 297         const unsigned long longdelay_ms = 50;
 298         unsigned long long ts;
 299
 300         /* We want a short delay sometimes to make a reader delay the grace
 301          * period, and we want a long delay occasionally to trigger
 302          * force_quiescent_state. */
 303
 304         if (!(torture_random(rrsp) % (nrealreaders * 2000 * longdelay_ms))) {
 305                 started = cur_ops->completed();
 306                 ts = rcu_trace_clock_local();
 307                 mdelay(longdelay_ms);
 308                 completed = cur_ops->completed();
 309                 do_trace_rcu_torture_read(cur_ops->name, NULL, ts,
 310                                           started, completed);
 311         }
 312         if (!(torture_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
 313                 udelay(shortdelay_us);
 314         if (!preempt_count() &&
 315             !(torture_random(rrsp) % (nrealreaders * 500)))
 316                 torture_preempt_schedule();  /* QS only if preemptible. */
 317 }
 318
 319 static void rcu_torture_read_unlock(int idx) __releases(RCU)
 320 {
 321         rcu_read_unlock();
 322 }
 323
 324 /*
 325  * Update callback in the pipe.  This should be invoked after a grace period.
 326  */
 327 static bool
 328 rcu_torture_pipe_update_one(struct rcu_torture *rp)
 329 {
 330         int i;
 331
 332         i = rp->rtort_pipe_count;
 333         if (i > RCU_TORTURE_PIPE_LEN)
 334                 i = RCU_TORTURE_PIPE_LEN;
 335         atomic_inc(&rcu_torture_wcount[i]);
 336         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 337                 rp->rtort_mbtest = 0;
 338                 return true;
 339         }
 340         return false;
 341 }
 342
 343 /*
 344  * Update all callbacks in the pipe.  Suitable for synchronous grace-period
 345  * primitives.
 346  */
 347 static void
 348 rcu_torture_pipe_update(struct rcu_torture *old_rp)
 349 {
 350         struct rcu_torture *rp;
 351         struct rcu_torture *rp1;
 352
 353         if (old_rp)
 354                 list_add(&old_rp->rtort_free, &rcu_torture_removed);
 355         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 356                 if (rcu_torture_pipe_update_one(rp)) {
 357                         list_del(&rp->rtort_free);
 358                         rcu_torture_free(rp);
 359                 }
 360         }
 361 }
 362
 363 static void
 364 rcu_torture_cb(struct rcu_head *p)
 365 {
 366         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 367
 368         if (torture_must_stop_irq()) {
 369                 /* Test is ending, just drop callbacks on the floor. */
 370                 /* The next initialization will pick up the pieces. */
 371                 return;
 372         }
 373         if (rcu_torture_pipe_update_one(rp))
 374                 rcu_torture_free(rp);
 375         else
 376                 cur_ops->deferred_free(rp);
 377 }
 378
 379 static unsigned long rcu_no_completed(void)
 380 {
 381         return 0;
 382 }
 383
 384 static void rcu_torture_deferred_free(struct rcu_torture *p)
 385 {
 386         call_rcu(&p->rtort_rcu, rcu_torture_cb);
 387 }
 388
 389 static void rcu_sync_torture_init(void)
 390 {
 391         INIT_LIST_HEAD(&rcu_torture_removed);
 392 }
 393
 394 static struct rcu_torture_ops rcu_ops = {
 395         .ttype          = RCU_FLAVOR,
 396         .init           = rcu_sync_torture_init,
 397         .readlock       = rcu_torture_read_lock,
 398         .read_delay     = rcu_read_delay,
 399         .readunlock     = rcu_torture_read_unlock,
 400         .started        = rcu_batches_started,
 401         .completed      = rcu_batches_completed,
 402         .deferred_free  = rcu_torture_deferred_free,
 403         .sync           = synchronize_rcu,
 404         .exp_sync       = synchronize_rcu_expedited,
 405         .get_state      = get_state_synchronize_rcu,
 406         .cond_sync      = cond_synchronize_rcu,
 407         .call           = call_rcu,
 408         .cb_barrier     = rcu_barrier,
 409         .fqs            = rcu_force_quiescent_state,
 410         .stats          = NULL,
 411         .irq_capable    = 1,
 412         .can_boost      = rcu_can_boost(),
 413         .name           = "rcu"
 414 };
 415
 416 /*
 417  * Definitions for rcu_bh torture testing.
 418  */
 419
 420 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
 421 {
 422         rcu_read_lock_bh();
 423         return 0;
 424 }
 425
 426 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
 427 {
 428         rcu_read_unlock_bh();
 429 }
 430
 431 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
 432 {
 433         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
 434 }
 435
 436 static struct rcu_torture_ops rcu_bh_ops = {
 437         .ttype          = RCU_BH_FLAVOR,
 438         .init           = rcu_sync_torture_init,
 439         .readlock       = rcu_bh_torture_read_lock,
 440         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 441         .readunlock     = rcu_bh_torture_read_unlock,
 442         .started        = rcu_batches_started_bh,
 443         .completed      = rcu_batches_completed_bh,
 444         .deferred_free  = rcu_bh_torture_deferred_free,
 445         .sync           = synchronize_rcu_bh,
 446         .exp_sync       = synchronize_rcu_bh_expedited,
 447         .call           = call_rcu_bh,
 448         .cb_barrier     = rcu_barrier_bh,
 449         .fqs            = rcu_bh_force_quiescent_state,
 450         .stats          = NULL,
 451         .irq_capable    = 1,
 452         .name           = "rcu_bh"
 453 };
 454
 455 /*
 456  * Don't even think about trying any of these in real life!!!
 457  * The names includes "busted", and they really means it!
 458  * The only purpose of these functions is to provide a buggy RCU
 459  * implementation to make sure that rcutorture correctly emits
 460  * buggy-RCU error messages.
 461  */
 462 static void rcu_busted_torture_deferred_free(struct rcu_torture *p)
 463 {
 464         /* This is a deliberate bug for testing purposes only! */
 465         rcu_torture_cb(&p->rtort_rcu);
 466 }
 467
 468 static void synchronize_rcu_busted(void)
 469 {
 470         /* This is a deliberate bug for testing purposes only! */
 471 }
 472
 473 static void
 474 call_rcu_busted(struct rcu_head *head, rcu_callback_t func)
 475 {
 476         /* This is a deliberate bug for testing purposes only! */
 477         func(head);
 478 }
 479
 480 static struct rcu_torture_ops rcu_busted_ops = {
 481         .ttype          = INVALID_RCU_FLAVOR,
 482         .init           = rcu_sync_torture_init,
 483         .readlock       = rcu_torture_read_lock,
 484         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 485         .readunlock     = rcu_torture_read_unlock,
 486         .started        = rcu_no_completed,
 487         .completed      = rcu_no_completed,
 488         .deferred_free  = rcu_busted_torture_deferred_free,
 489         .sync           = synchronize_rcu_busted,
 490         .exp_sync       = synchronize_rcu_busted,
 491         .call           = call_rcu_busted,
 492         .cb_barrier     = NULL,
 493         .fqs            = NULL,
 494         .stats          = NULL,
 495         .irq_capable    = 1,
 496         .name           = "busted"
 497 };
 498
 499 /*
 500  * Definitions for srcu torture testing.
 501  */
 502
 503 DEFINE_STATIC_SRCU(srcu_ctl);
 504 static struct srcu_struct srcu_ctld;
 505 static struct srcu_struct *srcu_ctlp = &srcu_ctl;
 506
 507 static int srcu_torture_read_lock(void) __acquires(srcu_ctlp)
 508 {
 509         return srcu_read_lock(srcu_ctlp);
 510 }
 511
 512 static void srcu_read_delay(struct torture_random_state *rrsp)
 513 {
 514         long delay;
 515         const long uspertick = 1000000 / HZ;
 516         const long longdelay = 10;
 517
 518         /* We want there to be long-running readers, but not all the time. */
 519
 520         delay = torture_random(rrsp) %
 521                 (nrealreaders * 2 * longdelay * uspertick);
 522         if (!delay && in_task())
 523                 schedule_timeout_interruptible(longdelay);
 524         else
 525                 rcu_read_delay(rrsp);
 526 }
 527
 528 static void srcu_torture_read_unlock(int idx) __releases(srcu_ctlp)
 529 {
 530         srcu_read_unlock(srcu_ctlp, idx);
 531 }
 532
 533 static unsigned long srcu_torture_completed(void)
 534 {
 535         return srcu_batches_completed(srcu_ctlp);
 536 }
 537
 538 static void srcu_torture_deferred_free(struct rcu_torture *rp)
 539 {
 540         call_srcu(srcu_ctlp, &rp->rtort_rcu, rcu_torture_cb);
 541 }
 542
 543 static void srcu_torture_synchronize(void)
 544 {
 545         synchronize_srcu(srcu_ctlp);
 546 }
 547
 548 static void srcu_torture_call(struct rcu_head *head,
 549                               rcu_callback_t func)
 550 {
 551         call_srcu(srcu_ctlp, head, func);
 552 }
 553
 554 static void srcu_torture_barrier(void)
 555 {
 556         srcu_barrier(srcu_ctlp);
 557 }
 558
 559 static void srcu_torture_stats(void)
 560 {
 561         srcu_torture_stats_print(srcu_ctlp, torture_type, TORTURE_FLAG);
 562 }
 563
 564 static void srcu_torture_synchronize_expedited(void)
 565 {
 566         synchronize_srcu_expedited(srcu_ctlp);
 567 }
 568
 569 static struct rcu_torture_ops srcu_ops = {
 570         .ttype          = SRCU_FLAVOR,
 571         .init           = rcu_sync_torture_init,
 572         .readlock       = srcu_torture_read_lock,
 573         .read_delay     = srcu_read_delay,
 574         .readunlock     = srcu_torture_read_unlock,
 575         .started        = NULL,
 576         .completed      = srcu_torture_completed,
 577         .deferred_free  = srcu_torture_deferred_free,
 578         .sync           = srcu_torture_synchronize,
 579         .exp_sync       = srcu_torture_synchronize_expedited,
 580         .call           = srcu_torture_call,
 581         .cb_barrier     = srcu_torture_barrier,
 582         .stats          = srcu_torture_stats,
 583         .irq_capable    = 1,
 584         .name           = "srcu"
 585 };
 586
 587 static void srcu_torture_init(void)
 588 {
 589         rcu_sync_torture_init();
 590         WARN_ON(init_srcu_struct(&srcu_ctld));
 591         srcu_ctlp = &srcu_ctld;
 592 }
 593
 594 static void srcu_torture_cleanup(void)
 595 {
 596         cleanup_srcu_struct(&srcu_ctld);
 597         srcu_ctlp = &srcu_ctl; /* In case of a later rcutorture run. */
 598 }
 599
 600 /* As above, but dynamically allocated. */
 601 static struct rcu_torture_ops srcud_ops = {
 602         .ttype          = SRCU_FLAVOR,
 603         .init           = srcu_torture_init,
 604         .cleanup        = srcu_torture_cleanup,
 605         .readlock       = srcu_torture_read_lock,
 606         .read_delay     = srcu_read_delay,
 607         .readunlock     = srcu_torture_read_unlock,
 608         .started        = NULL,
 609         .completed      = srcu_torture_completed,
 610         .deferred_free  = srcu_torture_deferred_free,
 611         .sync           = srcu_torture_synchronize,
 612         .exp_sync       = srcu_torture_synchronize_expedited,
 613         .call           = srcu_torture_call,
 614         .cb_barrier     = srcu_torture_barrier,
 615         .stats          = srcu_torture_stats,
 616         .irq_capable    = 1,
 617         .name           = "srcud"
 618 };
 619
 620 /*
 621  * Definitions for sched torture testing.
 622  */
 623
 624 static int sched_torture_read_lock(void)
 625 {
 626         preempt_disable();
 627         return 0;
 628 }
 629
 630 static void sched_torture_read_unlock(int idx)
 631 {
 632         preempt_enable();
 633 }
 634
 635 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
 636 {
 637         call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
 638 }
 639
 640 static struct rcu_torture_ops sched_ops = {
 641         .ttype          = RCU_SCHED_FLAVOR,
 642         .init           = rcu_sync_torture_init,
 643         .readlock       = sched_torture_read_lock,
 644         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 645         .readunlock     = sched_torture_read_unlock,
 646         .started        = rcu_batches_started_sched,
 647         .completed      = rcu_batches_completed_sched,
 648         .deferred_free  = rcu_sched_torture_deferred_free,
 649         .sync           = synchronize_sched,
 650         .exp_sync       = synchronize_sched_expedited,
 651         .get_state      = get_state_synchronize_sched,
 652         .cond_sync      = cond_synchronize_sched,
 653         .call           = call_rcu_sched,
 654         .cb_barrier     = rcu_barrier_sched,
 655         .fqs            = rcu_sched_force_quiescent_state,
 656         .stats          = NULL,
 657         .irq_capable    = 1,
 658         .name           = "sched"
 659 };
 660
 661 /*
 662  * Definitions for RCU-tasks torture testing.
 663  */
 664
 665 static int tasks_torture_read_lock(void)
 666 {
 667         return 0;
 668 }
 669
 670 static void tasks_torture_read_unlock(int idx)
 671 {
 672 }
 673
 674 static void rcu_tasks_torture_deferred_free(struct rcu_torture *p)
 675 {
 676         call_rcu_tasks(&p->rtort_rcu, rcu_torture_cb);
 677 }
 678
 679 static struct rcu_torture_ops tasks_ops = {
 680         .ttype          = RCU_TASKS_FLAVOR,
 681         .init           = rcu_sync_torture_init,
 682         .readlock       = tasks_torture_read_lock,
 683         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 684         .readunlock     = tasks_torture_read_unlock,
 685         .started        = rcu_no_completed,
 686         .completed      = rcu_no_completed,
 687         .deferred_free  = rcu_tasks_torture_deferred_free,
 688         .sync           = synchronize_rcu_tasks,
 689         .exp_sync       = synchronize_rcu_tasks,
 690         .call           = call_rcu_tasks,
 691         .cb_barrier     = rcu_barrier_tasks,
 692         .fqs            = NULL,
 693         .stats          = NULL,
 694         .irq_capable    = 1,
 695         .name           = "tasks"
 696 };
 697
 698 static bool __maybe_unused torturing_tasks(void)
 699 {
 700         return cur_ops == &tasks_ops;
 701 }
 702
 703 /*
 704  * RCU torture priority-boost testing.  Runs one real-time thread per
 705  * CPU for moderate bursts, repeatedly registering RCU callbacks and
 706  * spinning waiting for them to be invoked.  If a given callback takes
 707  * too long to be invoked, we assume that priority inversion has occurred.
 708  */
 709
 710 struct rcu_boost_inflight {
 711         struct rcu_head rcu;
 712         int inflight;
 713 };
 714
 715 static void rcu_torture_boost_cb(struct rcu_head *head)
 716 {
 717         struct rcu_boost_inflight *rbip =
 718                 container_of(head, struct rcu_boost_inflight, rcu);
 719
 720         /* Ensure RCU-core accesses precede clearing ->inflight */
 721         smp_store_release(&rbip->inflight, 0);
 722 }
 723
 724 static int rcu_torture_boost(void *arg)
 725 {
 726         unsigned long call_rcu_time;
 727         unsigned long endtime;
 728         unsigned long oldstarttime;
 729         struct rcu_boost_inflight rbi = { .inflight = 0 };
 730         struct sched_param sp;
 731
 732         VERBOSE_TOROUT_STRING("rcu_torture_boost started");
 733
 734         /* Set real-time priority. */
 735         sp.sched_priority = 1;
 736         if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
 737                 VERBOSE_TOROUT_STRING("rcu_torture_boost RT prio failed!");
 738                 n_rcu_torture_boost_rterror++;
 739         }
 740
 741         init_rcu_head_on_stack(&rbi.rcu);
 742         /* Each pass through the following loop does one boost-test cycle. */
 743         do {
 744                 /* Wait for the next test interval. */
 745                 oldstarttime = boost_starttime;
 746                 while (ULONG_CMP_LT(jiffies, oldstarttime)) {
 747                         schedule_timeout_interruptible(oldstarttime - jiffies);
 748                         stutter_wait("rcu_torture_boost");
 749                         if (torture_must_stop())
 750                                 goto checkwait;
 751                 }
 752
 753                 /* Do one boost-test interval. */
 754                 endtime = oldstarttime + test_boost_duration * HZ;
 755                 call_rcu_time = jiffies;
 756                 while (ULONG_CMP_LT(jiffies, endtime)) {
 757                         /* If we don't have a callback in flight, post one. */
 758                         if (!smp_load_acquire(&rbi.inflight)) {
 759                                 /* RCU core before ->inflight = 1. */
 760                                 smp_store_release(&rbi.inflight, 1);
 761                                 call_rcu(&rbi.rcu, rcu_torture_boost_cb);
 762                                 if (jiffies - call_rcu_time >
 763                                          test_boost_duration * HZ - HZ / 2) {
 764                                         VERBOSE_TOROUT_STRING("rcu_torture_boost boosting failed");
 765                                         n_rcu_torture_boost_failure++;
 766                                 }
 767                                 call_rcu_time = jiffies;
 768                         }
 769                         stutter_wait("rcu_torture_boost");
 770                         if (torture_must_stop())
 771                                 goto checkwait;
 772                 }
 773
 774                 /*
 775                  * Set the start time of the next test interval.
 776                  * Yes, this is vulnerable to long delays, but such
 777                  * delays simply cause a false negative for the next
 778                  * interval.  Besides, we are running at RT priority,
 779                  * so delays should be relatively rare.
 780                  */
 781                 while (oldstarttime == boost_starttime &&
 782                        !kthread_should_stop()) {
 783                         if (mutex_trylock(&boost_mutex)) {
 784                                 boost_starttime = jiffies +
 785                                                   test_boost_interval * HZ;
 786                                 n_rcu_torture_boosts++;
 787                                 mutex_unlock(&boost_mutex);
 788                                 break;
 789                         }
 790                         schedule_timeout_uninterruptible(1);
 791                 }
 792
 793                 /* Go do the stutter. */
 794 checkwait:      stutter_wait("rcu_torture_boost");
 795         } while (!torture_must_stop());
 796
 797         /* Clean up and exit. */
 798         while (!kthread_should_stop() || smp_load_acquire(&rbi.inflight)) {
 799                 torture_shutdown_absorb("rcu_torture_boost");
 800                 schedule_timeout_uninterruptible(1);
 801         }
 802         destroy_rcu_head_on_stack(&rbi.rcu);
 803         torture_kthread_stopping("rcu_torture_boost");
 804         return 0;
 805 }
 806
 807 static void rcu_torture_cbflood_cb(struct rcu_head *rhp)
 808 {
 809 }
 810
 811 /*
 812  * RCU torture callback-flood kthread.  Repeatedly induces bursts of calls
 813  * to call_rcu() or analogous, increasing the probability of occurrence
 814  * of callback-overflow corner cases.
 815  */
 816 static int
 817 rcu_torture_cbflood(void *arg)
 818 {
 819         int err = 1;
 820         int i;
 821         int j;
 822         struct rcu_head *rhp;
 823
 824         if (cbflood_n_per_burst > 0 &&
 825             cbflood_inter_holdoff > 0 &&
 826             cbflood_intra_holdoff > 0 &&
 827             cur_ops->call &&
 828             cur_ops->cb_barrier) {
 829                 rhp = vmalloc(sizeof(*rhp) *
 830                               cbflood_n_burst * cbflood_n_per_burst);
 831                 err = !rhp;
 832         }
 833         if (err) {
 834                 VERBOSE_TOROUT_STRING("rcu_torture_cbflood disabled: Bad args or OOM");
 835                 goto wait_for_stop;
 836         }
 837         VERBOSE_TOROUT_STRING("rcu_torture_cbflood task started");
 838         do {
 839                 schedule_timeout_interruptible(cbflood_inter_holdoff);
 840                 atomic_long_inc(&n_cbfloods);
 841                 WARN_ON(signal_pending(current));
 842                 for (i = 0; i < cbflood_n_burst; i++) {
 843                         for (j = 0; j < cbflood_n_per_burst; j++) {
 844                                 cur_ops->call(&rhp[i * cbflood_n_per_burst + j],
 845                                               rcu_torture_cbflood_cb);
 846                         }
 847                         schedule_timeout_interruptible(cbflood_intra_holdoff);
 848                         WARN_ON(signal_pending(current));
 849                 }
 850                 cur_ops->cb_barrier();
 851                 stutter_wait("rcu_torture_cbflood");
 852         } while (!torture_must_stop());
 853         vfree(rhp);
 854 wait_for_stop:
 855         torture_kthread_stopping("rcu_torture_cbflood");
 856         return 0;
 857 }
 858
 859 /*
 860  * RCU torture force-quiescent-state kthread.  Repeatedly induces
 861  * bursts of calls to force_quiescent_state(), increasing the probability
 862  * of occurrence of some important types of race conditions.
 863  */
 864 static int
 865 rcu_torture_fqs(void *arg)
 866 {
 867         unsigned long fqs_resume_time;
 868         int fqs_burst_remaining;
 869
 870         VERBOSE_TOROUT_STRING("rcu_torture_fqs task started");
 871         do {
 872                 fqs_resume_time = jiffies + fqs_stutter * HZ;
 873                 while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
 874                        !kthread_should_stop()) {
 875                         schedule_timeout_interruptible(1);
 876                 }
 877                 fqs_burst_remaining = fqs_duration;
 878                 while (fqs_burst_remaining > 0 &&
 879                        !kthread_should_stop()) {
 880                         cur_ops->fqs();
 881                         udelay(fqs_holdoff);
 882                         fqs_burst_remaining -= fqs_holdoff;
 883                 }
 884                 stutter_wait("rcu_torture_fqs");
 885         } while (!torture_must_stop());
 886         torture_kthread_stopping("rcu_torture_fqs");
 887         return 0;
 888 }
 889
 890 /*
 891  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 892  * for that pointed to by rcu_torture_current, freeing the old structure
 893  * after a series of grace periods (the "pipeline").
 894  */
 895 static int
 896 rcu_torture_writer(void *arg)
 897 {
 898         bool can_expedite = !rcu_gp_is_expedited() && !rcu_gp_is_normal();
 899         int expediting = 0;
 900         unsigned long gp_snap;
 901         bool gp_cond1 = gp_cond, gp_exp1 = gp_exp, gp_normal1 = gp_normal;
 902         bool gp_sync1 = gp_sync;
 903         int i;
 904         struct rcu_torture *rp;
 905         struct rcu_torture *old_rp;
 906         static DEFINE_TORTURE_RANDOM(rand);
 907         int synctype[] = { RTWS_DEF_FREE, RTWS_EXP_SYNC,
 908                            RTWS_COND_GET, RTWS_SYNC };
 909         int nsynctypes = 0;
 910
 911         VERBOSE_TOROUT_STRING("rcu_torture_writer task started");
 912         if (!can_expedite) {
 913                 pr_alert("%s" TORTURE_FLAG
 914                          " GP expediting controlled from boot/sysfs for %s,\n",
 915                          torture_type, cur_ops->name);
 916                 pr_alert("%s" TORTURE_FLAG
 917                          " Disabled dynamic grace-period expediting.\n",
 918                          torture_type);
 919         }
 920
 921         /* Initialize synctype[] array.  If none set, take default. */
 922         if (!gp_cond1 && !gp_exp1 && !gp_normal1 && !gp_sync1)
 923                 gp_cond1 = gp_exp1 = gp_normal1 = gp_sync1 = true;
 924         if (gp_cond1 && cur_ops->get_state && cur_ops->cond_sync)
 925                 synctype[nsynctypes++] = RTWS_COND_GET;
 926         else if (gp_cond && (!cur_ops->get_state || !cur_ops->cond_sync))
 927                 pr_alert("rcu_torture_writer: gp_cond without primitives.\n");
 928         if (gp_exp1 && cur_ops->exp_sync)
 929                 synctype[nsynctypes++] = RTWS_EXP_SYNC;
 930         else if (gp_exp && !cur_ops->exp_sync)
 931                 pr_alert("rcu_torture_writer: gp_exp without primitives.\n");
 932         if (gp_normal1 && cur_ops->deferred_free)
 933                 synctype[nsynctypes++] = RTWS_DEF_FREE;
 934         else if (gp_normal && !cur_ops->deferred_free)
 935                 pr_alert("rcu_torture_writer: gp_normal without primitives.\n");
 936         if (gp_sync1 && cur_ops->sync)
 937                 synctype[nsynctypes++] = RTWS_SYNC;
 938         else if (gp_sync && !cur_ops->sync)
 939                 pr_alert("rcu_torture_writer: gp_sync without primitives.\n");
 940         if (WARN_ONCE(nsynctypes == 0,
 941                       "rcu_torture_writer: No update-side primitives.\n")) {
 942                 /*
 943                  * No updates primitives, so don't try updating.
 944                  * The resulting test won't be testing much, hence the
 945                  * above WARN_ONCE().
 946                  */
 947                 rcu_torture_writer_state = RTWS_STOPPING;
 948                 torture_kthread_stopping("rcu_torture_writer");
 949         }
 950
 951         do {
 952                 rcu_torture_writer_state = RTWS_FIXED_DELAY;
 953                 schedule_timeout_uninterruptible(1);
 954                 rp = rcu_torture_alloc();
 955                 if (rp == NULL)
 956                         continue;
 957                 rp->rtort_pipe_count = 0;
 958                 rcu_torture_writer_state = RTWS_DELAY;
 959                 udelay(torture_random(&rand) & 0x3ff);
 960                 rcu_torture_writer_state = RTWS_REPLACE;
 961                 old_rp = rcu_dereference_check(rcu_torture_current,
 962                                                current == writer_task);
 963                 rp->rtort_mbtest = 1;
 964                 rcu_assign_pointer(rcu_torture_current, rp);
 965                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
 966                 if (old_rp) {
 967                         i = old_rp->rtort_pipe_count;
 968                         if (i > RCU_TORTURE_PIPE_LEN)
 969                                 i = RCU_TORTURE_PIPE_LEN;
 970                         atomic_inc(&rcu_torture_wcount[i]);
 971                         old_rp->rtort_pipe_count++;
 972                         switch (synctype[torture_random(&rand) % nsynctypes]) {
 973                         case RTWS_DEF_FREE:
 974                                 rcu_torture_writer_state = RTWS_DEF_FREE;
 975                                 cur_ops->deferred_free(old_rp);
 976                                 break;
 977                         case RTWS_EXP_SYNC:
 978                                 rcu_torture_writer_state = RTWS_EXP_SYNC;
 979                                 cur_ops->exp_sync();
 980                                 rcu_torture_pipe_update(old_rp);
 981                                 break;
 982                         case RTWS_COND_GET:
 983                                 rcu_torture_writer_state = RTWS_COND_GET;
 984                                 gp_snap = cur_ops->get_state();
 985                                 i = torture_random(&rand) % 16;
 986                                 if (i != 0)
 987                                         schedule_timeout_interruptible(i);
 988                                 udelay(torture_random(&rand) % 1000);
 989                                 rcu_torture_writer_state = RTWS_COND_SYNC;
 990                                 cur_ops->cond_sync(gp_snap);
 991                                 rcu_torture_pipe_update(old_rp);
 992                                 break;
 993                         case RTWS_SYNC:
 994                                 rcu_torture_writer_state = RTWS_SYNC;
 995                                 cur_ops->sync();
 996                                 rcu_torture_pipe_update(old_rp);
 997                                 break;
 998                         default:
 999                                 WARN_ON_ONCE(1);
1000                                 break;
1001                         }
1002                 }
1003                 rcutorture_record_progress(++rcu_torture_current_version);
1004                 /* Cycle through nesting levels of rcu_expedite_gp() calls. */
1005                 if (can_expedite &&
1006                     !(torture_random(&rand) & 0xff & (!!expediting - 1))) {
1007                         WARN_ON_ONCE(expediting == 0 && rcu_gp_is_expedited());
1008                         if (expediting >= 0)
1009                                 rcu_expedite_gp();
1010                         else
1011                                 rcu_unexpedite_gp();
1012                         if (++expediting > 3)
1013                                 expediting = -expediting;
1014                 }
1015                 rcu_torture_writer_state = RTWS_STUTTER;
1016                 stutter_wait("rcu_torture_writer");
1017         } while (!torture_must_stop());
1018         /* Reset expediting back to unexpedited. */
1019         if (expediting > 0)
1020                 expediting = -expediting;
1021         while (can_expedite && expediting++ < 0)
1022                 rcu_unexpedite_gp();
1023         WARN_ON_ONCE(can_expedite && rcu_gp_is_expedited());
1024         rcu_torture_writer_state = RTWS_STOPPING;
1025         torture_kthread_stopping("rcu_torture_writer");
1026         return 0;
1027 }
1028
1029 /*
1030  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
1031  * delay between calls.
1032  */
1033 static int
1034 rcu_torture_fakewriter(void *arg)
1035 {
1036         DEFINE_TORTURE_RANDOM(rand);
1037
1038         VERBOSE_TOROUT_STRING("rcu_torture_fakewriter task started");
1039         set_user_nice(current, MAX_NICE);
1040
1041         do {
1042                 schedule_timeout_uninterruptible(1 + torture_random(&rand)%10);
1043                 udelay(torture_random(&rand) & 0x3ff);
1044                 if (cur_ops->cb_barrier != NULL &&
1045                     torture_random(&rand) % (nfakewriters * 8) == 0) {
1046                         cur_ops->cb_barrier();
1047                 } else if (gp_normal == gp_exp) {
1048                         if (torture_random(&rand) & 0x80)
1049                                 cur_ops->sync();
1050                         else
1051                                 cur_ops->exp_sync();
1052                 } else if (gp_normal) {
1053                         cur_ops->sync();
1054                 } else {
1055                         cur_ops->exp_sync();
1056                 }
1057                 stutter_wait("rcu_torture_fakewriter");
1058         } while (!torture_must_stop());
1059
1060         torture_kthread_stopping("rcu_torture_fakewriter");
1061         return 0;
1062 }
1063
1064 static void rcu_torture_timer_cb(struct rcu_head *rhp)
1065 {
1066         kfree(rhp);
1067 }
1068
1069 /*
1070  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
1071  * incrementing the corresponding element of the pipeline array.  The
1072  * counter in the element should never be greater than 1, otherwise, the
1073  * RCU implementation is broken.
1074  */
1075 static void rcu_torture_timer(struct timer_list *unused)
1076 {
1077         int idx;
1078         unsigned long started;
1079         unsigned long completed;
1080         static DEFINE_TORTURE_RANDOM(rand);
1081         static DEFINE_SPINLOCK(rand_lock);
1082         struct rcu_torture *p;
1083         int pipe_count;
1084         unsigned long long ts;
1085
1086         idx = cur_ops->readlock();
1087         if (cur_ops->started)
1088                 started = cur_ops->started();
1089         else
1090                 started = cur_ops->completed();
1091         ts = rcu_trace_clock_local();
1092         p = rcu_dereference_check(rcu_torture_current,
1093                                   rcu_read_lock_bh_held() ||
1094                                   rcu_read_lock_sched_held() ||
1095                                   srcu_read_lock_held(srcu_ctlp) ||
1096                                   torturing_tasks());
1097         if (p == NULL) {
1098                 /* Leave because rcu_torture_writer is not yet underway */
1099                 cur_ops->readunlock(idx);
1100                 return;
1101         }
1102         if (p->rtort_mbtest == 0)
1103                 atomic_inc(&n_rcu_torture_mberror);
1104         spin_lock(&rand_lock);
1105         cur_ops->read_delay(&rand);
1106         n_rcu_torture_timers++;
1107         spin_unlock(&rand_lock);
1108         preempt_disable();
1109         pipe_count = p->rtort_pipe_count;
1110         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1111                 /* Should not happen, but... */
1112                 pipe_count = RCU_TORTURE_PIPE_LEN;
1113         }
1114         completed = cur_ops->completed();
1115         if (pipe_count > 1) {
1116                 do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu, ts,
1117                                           started, completed);
1118                 rcu_ftrace_dump(DUMP_ALL);
1119         }
1120         __this_cpu_inc(rcu_torture_count[pipe_count]);
1121         completed = completed - started;
1122         if (cur_ops->started)
1123                 completed++;
1124         if (completed > RCU_TORTURE_PIPE_LEN) {
1125                 /* Should not happen, but... */
1126                 completed = RCU_TORTURE_PIPE_LEN;
1127         }
1128         __this_cpu_inc(rcu_torture_batch[completed]);
1129         preempt_enable();
1130         cur_ops->readunlock(idx);
1131
1132         /* Test call_rcu() invocation from interrupt handler. */
1133         if (cur_ops->call) {
1134                 struct rcu_head *rhp = kmalloc(sizeof(*rhp), GFP_NOWAIT);
1135
1136                 if (rhp)
1137                         cur_ops->call(rhp, rcu_torture_timer_cb);
1138         }
1139 }
1140
1141 /*
1142  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
1143  * incrementing the corresponding element of the pipeline array.  The
1144  * counter in the element should never be greater than 1, otherwise, the
1145  * RCU implementation is broken.
1146  */
1147 static int
1148 rcu_torture_reader(void *arg)
1149 {
1150         unsigned long started;
1151         unsigned long completed;
1152         int idx;
1153         DEFINE_TORTURE_RANDOM(rand);
1154         struct rcu_torture *p;
1155         int pipe_count;
1156         struct timer_list t;
1157         unsigned long long ts;
1158
1159         VERBOSE_TOROUT_STRING("rcu_torture_reader task started");
1160         set_user_nice(current, MAX_NICE);
1161         if (irqreader && cur_ops->irq_capable)
1162                 timer_setup_on_stack(&t, rcu_torture_timer, 0);
1163
1164         do {
1165                 if (irqreader && cur_ops->irq_capable) {
1166                         if (!timer_pending(&t))
1167                                 mod_timer(&t, jiffies + 1);
1168                 }
1169                 idx = cur_ops->readlock();
1170                 if (cur_ops->started)
1171                         started = cur_ops->started();
1172                 else
1173                         started = cur_ops->completed();
1174                 ts = rcu_trace_clock_local();
1175                 p = rcu_dereference_check(rcu_torture_current,
1176                                           rcu_read_lock_bh_held() ||
1177                                           rcu_read_lock_sched_held() ||
1178                                           srcu_read_lock_held(srcu_ctlp) ||
1179                                           torturing_tasks());
1180                 if (p == NULL) {
1181                         /* Wait for rcu_torture_writer to get underway */
1182                         cur_ops->readunlock(idx);
1183                         schedule_timeout_interruptible(HZ);
1184                         continue;
1185                 }
1186                 if (p->rtort_mbtest == 0)
1187                         atomic_inc(&n_rcu_torture_mberror);
1188                 cur_ops->read_delay(&rand);
1189                 preempt_disable();
1190                 pipe_count = p->rtort_pipe_count;
1191                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1192                         /* Should not happen, but... */
1193                         pipe_count = RCU_TORTURE_PIPE_LEN;
1194                 }
1195                 completed = cur_ops->completed();
1196                 if (pipe_count > 1) {
1197                         do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu,
1198                                                   ts, started, completed);
1199                         rcu_ftrace_dump(DUMP_ALL);
1200                 }
1201                 __this_cpu_inc(rcu_torture_count[pipe_count]);
1202                 completed = completed - started;
1203                 if (cur_ops->started)
1204                         completed++;
1205                 if (completed > RCU_TORTURE_PIPE_LEN) {
1206                         /* Should not happen, but... */
1207                         completed = RCU_TORTURE_PIPE_LEN;
1208                 }
1209                 __this_cpu_inc(rcu_torture_batch[completed]);
1210                 preempt_enable();
1211                 cur_ops->readunlock(idx);
1212                 stutter_wait("rcu_torture_reader");
1213         } while (!torture_must_stop());
1214         if (irqreader && cur_ops->irq_capable) {
1215                 del_timer_sync(&t);
1216                 destroy_timer_on_stack(&t);
1217         }
1218         torture_kthread_stopping("rcu_torture_reader");
1219         return 0;
1220 }
1221
1222 /*
1223  * Print torture statistics.  Caller must ensure that there is only
1224  * one call to this function at a given time!!!  This is normally
1225  * accomplished by relying on the module system to only have one copy
1226  * of the module loaded, and then by giving the rcu_torture_stats
1227  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1228  * thread is not running).
1229  */
1230 static void
1231 rcu_torture_stats_print(void)
1232 {
1233         int cpu;
1234         int i;
1235         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1236         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1237         static unsigned long rtcv_snap = ULONG_MAX;
1238         static bool splatted;
1239         struct task_struct *wtp;
1240
1241         for_each_possible_cpu(cpu) {
1242                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1243                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1244                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1245                 }
1246         }
1247         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1248                 if (pipesummary[i] != 0)
1249                         break;
1250         }
1251
1252         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1253         pr_cont("rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
1254                 rcu_torture_current,
1255                 rcu_torture_current_version,
1256                 list_empty(&rcu_torture_freelist),
1257                 atomic_read(&n_rcu_torture_alloc),
1258                 atomic_read(&n_rcu_torture_alloc_fail),
1259                 atomic_read(&n_rcu_torture_free));
1260         pr_cont("rtmbe: %d rtbe: %ld rtbke: %ld rtbre: %ld ",
1261                 atomic_read(&n_rcu_torture_mberror),
1262                 n_rcu_torture_barrier_error,
1263                 n_rcu_torture_boost_ktrerror,
1264                 n_rcu_torture_boost_rterror);
1265         pr_cont("rtbf: %ld rtb: %ld nt: %ld ",
1266                 n_rcu_torture_boost_failure,
1267                 n_rcu_torture_boosts,
1268                 n_rcu_torture_timers);
1269         torture_onoff_stats();
1270         pr_cont("barrier: %ld/%ld:%ld ",
1271                 n_barrier_successes,
1272                 n_barrier_attempts,
1273                 n_rcu_torture_barrier_error);
1274         pr_cont("cbflood: %ld\n", atomic_long_read(&n_cbfloods));
1275
1276         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1277         if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1278             n_rcu_torture_barrier_error != 0 ||
1279             n_rcu_torture_boost_ktrerror != 0 ||
1280             n_rcu_torture_boost_rterror != 0 ||
1281             n_rcu_torture_boost_failure != 0 ||
1282             i > 1) {
1283                 pr_cont("%s", "!!! ");
1284                 atomic_inc(&n_rcu_torture_error);
1285                 WARN_ON_ONCE(1);
1286         }
1287         pr_cont("Reader Pipe: ");
1288         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1289                 pr_cont(" %ld", pipesummary[i]);
1290         pr_cont("\n");
1291
1292         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1293         pr_cont("Reader Batch: ");
1294         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1295                 pr_cont(" %ld", batchsummary[i]);
1296         pr_cont("\n");
1297
1298         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1299         pr_cont("Free-Block Circulation: ");
1300         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1301                 pr_cont(" %d", atomic_read(&rcu_torture_wcount[i]));
1302         }
1303         pr_cont("\n");
1304
1305         if (cur_ops->stats)
1306                 cur_ops->stats();
1307         if (rtcv_snap == rcu_torture_current_version &&
1308             rcu_torture_current != NULL) {
1309                 int __maybe_unused flags = 0;
1310                 unsigned long __maybe_unused gpnum = 0;
1311                 unsigned long __maybe_unused completed = 0;
1312
1313                 rcutorture_get_gp_data(cur_ops->ttype,
1314                                        &flags, &gpnum, &completed);
1315                 srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp,
1316                                         &flags, &gpnum, &completed);
1317                 wtp = READ_ONCE(writer_task);
1318                 pr_alert("??? Writer stall state %s(%d) g%lu c%lu f%#x ->state %#lx cpu %d\n",
1319                          rcu_torture_writer_state_getname(),
1320                          rcu_torture_writer_state,
1321                          gpnum, completed, flags,
1322                          wtp == NULL ? ~0UL : wtp->state,
1323                          wtp == NULL ? -1 : (int)task_cpu(wtp));
1324                 if (!splatted && wtp) {
1325                         sched_show_task(wtp);
1326                         splatted = true;
1327                 }
1328                 show_rcu_gp_kthreads();
1329                 rcu_ftrace_dump(DUMP_ALL);
1330         }
1331         rtcv_snap = rcu_torture_current_version;
1332 }
1333
1334 /*
1335  * Periodically prints torture statistics, if periodic statistics printing
1336  * was specified via the stat_interval module parameter.
1337  */
1338 static int
1339 rcu_torture_stats(void *arg)
1340 {
1341         VERBOSE_TOROUT_STRING("rcu_torture_stats task started");
1342         do {
1343                 schedule_timeout_interruptible(stat_interval * HZ);
1344                 rcu_torture_stats_print();
1345                 torture_shutdown_absorb("rcu_torture_stats");
1346         } while (!torture_must_stop());
1347         torture_kthread_stopping("rcu_torture_stats");
1348         return 0;
1349 }
1350
1351 static inline void
1352 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
1353 {
1354         pr_alert("%s" TORTURE_FLAG
1355                  "--- %s: nreaders=%d nfakewriters=%d "
1356                  "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1357                  "shuffle_interval=%d stutter=%d irqreader=%d "
1358                  "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1359                  "test_boost=%d/%d test_boost_interval=%d "
1360                  "test_boost_duration=%d shutdown_secs=%d "
1361                  "stall_cpu=%d stall_cpu_holdoff=%d stall_cpu_irqsoff=%d "
1362                  "n_barrier_cbs=%d "
1363                  "onoff_interval=%d onoff_holdoff=%d\n",
1364                  torture_type, tag, nrealreaders, nfakewriters,
1365                  stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1366                  stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1367                  test_boost, cur_ops->can_boost,
1368                  test_boost_interval, test_boost_duration, shutdown_secs,
1369                  stall_cpu, stall_cpu_holdoff, stall_cpu_irqsoff,
1370                  n_barrier_cbs,
1371                  onoff_interval, onoff_holdoff);
1372 }
1373
1374 static int rcutorture_booster_cleanup(unsigned int cpu)
1375 {
1376         struct task_struct *t;
1377
1378         if (boost_tasks[cpu] == NULL)
1379                 return 0;
1380         mutex_lock(&boost_mutex);
1381         t = boost_tasks[cpu];
1382         boost_tasks[cpu] = NULL;
1383         mutex_unlock(&boost_mutex);
1384
1385         /* This must be outside of the mutex, otherwise deadlock! */
1386         torture_stop_kthread(rcu_torture_boost, t);
1387         return 0;
1388 }
1389
1390 static int rcutorture_booster_init(unsigned int cpu)
1391 {
1392         int retval;
1393
1394         if (boost_tasks[cpu] != NULL)
1395                 return 0;  /* Already created, nothing more to do. */
1396
1397         /* Don't allow time recalculation while creating a new task. */
1398         mutex_lock(&boost_mutex);
1399         VERBOSE_TOROUT_STRING("Creating rcu_torture_boost task");
1400         boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1401                                                   cpu_to_node(cpu),
1402                                                   "rcu_torture_boost");
1403         if (IS_ERR(boost_tasks[cpu])) {
1404                 retval = PTR_ERR(boost_tasks[cpu]);
1405                 VERBOSE_TOROUT_STRING("rcu_torture_boost task create failed");
1406                 n_rcu_torture_boost_ktrerror++;
1407                 boost_tasks[cpu] = NULL;
1408                 mutex_unlock(&boost_mutex);
1409                 return retval;
1410         }
1411         kthread_bind(boost_tasks[cpu], cpu);
1412         wake_up_process(boost_tasks[cpu]);
1413         mutex_unlock(&boost_mutex);
1414         return 0;
1415 }
1416
1417 /*
1418  * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then
1419  * induces a CPU stall for the time specified by stall_cpu.
1420  */
1421 static int rcu_torture_stall(void *args)
1422 {
1423         unsigned long stop_at;
1424
1425         VERBOSE_TOROUT_STRING("rcu_torture_stall task started");
1426         if (stall_cpu_holdoff > 0) {
1427                 VERBOSE_TOROUT_STRING("rcu_torture_stall begin holdoff");
1428                 schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
1429                 VERBOSE_TOROUT_STRING("rcu_torture_stall end holdoff");
1430         }
1431         if (!kthread_should_stop()) {
1432                 stop_at = get_seconds() + stall_cpu;
1433                 /* RCU CPU stall is expected behavior in following code. */
1434                 rcu_read_lock();
1435                 if (stall_cpu_irqsoff)
1436                         local_irq_disable();
1437                 else
1438                         preempt_disable();
1439                 pr_alert("rcu_torture_stall start on CPU %d.\n",
1440                          smp_processor_id());
1441                 while (ULONG_CMP_LT(get_seconds(), stop_at))
1442                         continue;  /* Induce RCU CPU stall warning. */
1443                 if (stall_cpu_irqsoff)
1444                         local_irq_enable();
1445                 else
1446                         preempt_enable();
1447                 rcu_read_unlock();
1448                 pr_alert("rcu_torture_stall end.\n");
1449         }
1450         torture_shutdown_absorb("rcu_torture_stall");
1451         while (!kthread_should_stop())
1452                 schedule_timeout_interruptible(10 * HZ);
1453         return 0;
1454 }
1455
1456 /* Spawn CPU-stall kthread, if stall_cpu specified. */
1457 static int __init rcu_torture_stall_init(void)
1458 {
1459         if (stall_cpu <= 0)
1460                 return 0;
1461         return torture_create_kthread(rcu_torture_stall, NULL, stall_task);
1462 }
1463
1464 /* Callback function for RCU barrier testing. */
1465 static void rcu_torture_barrier_cbf(struct rcu_head *rcu)
1466 {
1467         atomic_inc(&barrier_cbs_invoked);
1468 }
1469
1470 /* kthread function to register callbacks used to test RCU barriers. */
1471 static int rcu_torture_barrier_cbs(void *arg)
1472 {
1473         long myid = (long)arg;
1474         bool lastphase = 0;
1475         bool newphase;
1476         struct rcu_head rcu;
1477
1478         init_rcu_head_on_stack(&rcu);
1479         VERBOSE_TOROUT_STRING("rcu_torture_barrier_cbs task started");
1480         set_user_nice(current, MAX_NICE);
1481         do {
1482                 wait_event(barrier_cbs_wq[myid],
1483                            (newphase =
1484                             smp_load_acquire(&barrier_phase)) != lastphase ||
1485                            torture_must_stop());
1486                 lastphase = newphase;
1487                 if (torture_must_stop())
1488                         break;
1489                 /*
1490                  * The above smp_load_acquire() ensures barrier_phase load
1491                  * is ordered before the following ->call().
1492                  */
1493                 local_irq_disable(); /* Just to test no-irq call_rcu(). */
1494                 cur_ops->call(&rcu, rcu_torture_barrier_cbf);
1495                 local_irq_enable();
1496                 if (atomic_dec_and_test(&barrier_cbs_count))
1497                         wake_up(&barrier_wq);
1498         } while (!torture_must_stop());
1499         if (cur_ops->cb_barrier != NULL)
1500                 cur_ops->cb_barrier();
1501         destroy_rcu_head_on_stack(&rcu);
1502         torture_kthread_stopping("rcu_torture_barrier_cbs");
1503         return 0;
1504 }
1505
1506 /* kthread function to drive and coordinate RCU barrier testing. */
1507 static int rcu_torture_barrier(void *arg)
1508 {
1509         int i;
1510
1511         VERBOSE_TOROUT_STRING("rcu_torture_barrier task starting");
1512         do {
1513                 atomic_set(&barrier_cbs_invoked, 0);
1514                 atomic_set(&barrier_cbs_count, n_barrier_cbs);
1515                 /* Ensure barrier_phase ordered after prior assignments. */
1516                 smp_store_release(&barrier_phase, !barrier_phase);
1517                 for (i = 0; i < n_barrier_cbs; i++)
1518                         wake_up(&barrier_cbs_wq[i]);
1519                 wait_event(barrier_wq,
1520                            atomic_read(&barrier_cbs_count) == 0 ||
1521                            torture_must_stop());
1522                 if (torture_must_stop())
1523                         break;
1524                 n_barrier_attempts++;
1525                 cur_ops->cb_barrier(); /* Implies smp_mb() for wait_event(). */
1526                 if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
1527                         n_rcu_torture_barrier_error++;
1528                         pr_err("barrier_cbs_invoked = %d, n_barrier_cbs = %d\n",
1529                                atomic_read(&barrier_cbs_invoked),
1530                                n_barrier_cbs);
1531                         WARN_ON_ONCE(1);
1532                 }
1533                 n_barrier_successes++;
1534                 schedule_timeout_interruptible(HZ / 10);
1535         } while (!torture_must_stop());
1536         torture_kthread_stopping("rcu_torture_barrier");
1537         return 0;
1538 }
1539
1540 /* Initialize RCU barrier testing. */
1541 static int rcu_torture_barrier_init(void)
1542 {
1543         int i;
1544         int ret;
1545
1546         if (n_barrier_cbs <= 0)
1547                 return 0;
1548         if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
1549                 pr_alert("%s" TORTURE_FLAG
1550                          " Call or barrier ops missing for %s,\n",
1551                          torture_type, cur_ops->name);
1552                 pr_alert("%s" TORTURE_FLAG
1553                          " RCU barrier testing omitted from run.\n",
1554                          torture_type);
1555                 return 0;
1556         }
1557         atomic_set(&barrier_cbs_count, 0);
1558         atomic_set(&barrier_cbs_invoked, 0);
1559         barrier_cbs_tasks =
1560                 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_tasks[0]),
1561                         GFP_KERNEL);
1562         barrier_cbs_wq =
1563                 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_wq[0]),
1564                         GFP_KERNEL);
1565         if (barrier_cbs_tasks == NULL || !barrier_cbs_wq)
1566                 return -ENOMEM;
1567         for (i = 0; i < n_barrier_cbs; i++) {
1568                 init_waitqueue_head(&barrier_cbs_wq[i]);
1569                 ret = torture_create_kthread(rcu_torture_barrier_cbs,
1570                                              (void *)(long)i,
1571                                              barrier_cbs_tasks[i]);
1572                 if (ret)
1573                         return ret;
1574         }
1575         return torture_create_kthread(rcu_torture_barrier, NULL, barrier_task);
1576 }
1577
1578 /* Clean up after RCU barrier testing. */
1579 static void rcu_torture_barrier_cleanup(void)
1580 {
1581         int i;
1582
1583         torture_stop_kthread(rcu_torture_barrier, barrier_task);
1584         if (barrier_cbs_tasks != NULL) {
1585                 for (i = 0; i < n_barrier_cbs; i++)
1586                         torture_stop_kthread(rcu_torture_barrier_cbs,
1587                                              barrier_cbs_tasks[i]);
1588                 kfree(barrier_cbs_tasks);
1589                 barrier_cbs_tasks = NULL;
1590         }
1591         if (barrier_cbs_wq != NULL) {
1592                 kfree(barrier_cbs_wq);
1593                 barrier_cbs_wq = NULL;
1594         }
1595 }
1596
1597 static enum cpuhp_state rcutor_hp;
1598
1599 static void
1600 rcu_torture_cleanup(void)
1601 {
1602         int i;
1603
1604         rcutorture_record_test_transition();
1605         if (torture_cleanup_begin()) {
1606                 if (cur_ops->cb_barrier != NULL)
1607                         cur_ops->cb_barrier();
1608                 return;
1609         }
1610
1611         rcu_torture_barrier_cleanup();
1612         torture_stop_kthread(rcu_torture_stall, stall_task);
1613         torture_stop_kthread(rcu_torture_writer, writer_task);
1614
1615         if (reader_tasks) {
1616                 for (i = 0; i < nrealreaders; i++)
1617                         torture_stop_kthread(rcu_torture_reader,
1618                                              reader_tasks[i]);
1619                 kfree(reader_tasks);
1620         }
1621         rcu_torture_current = NULL;
1622
1623         if (fakewriter_tasks) {
1624                 for (i = 0; i < nfakewriters; i++) {
1625                         torture_stop_kthread(rcu_torture_fakewriter,
1626                                              fakewriter_tasks[i]);
1627                 }
1628                 kfree(fakewriter_tasks);
1629                 fakewriter_tasks = NULL;
1630         }
1631
1632         torture_stop_kthread(rcu_torture_stats, stats_task);
1633         torture_stop_kthread(rcu_torture_fqs, fqs_task);
1634         for (i = 0; i < ncbflooders; i++)
1635                 torture_stop_kthread(rcu_torture_cbflood, cbflood_task[i]);
1636         if ((test_boost == 1 && cur_ops->can_boost) ||
1637             test_boost == 2)
1638                 cpuhp_remove_state(rcutor_hp);
1639
1640         /*
1641          * Wait for all RCU callbacks to fire, then do flavor-specific
1642          * cleanup operations.
1643          */
1644         if (cur_ops->cb_barrier != NULL)
1645                 cur_ops->cb_barrier();
1646         if (cur_ops->cleanup != NULL)
1647                 cur_ops->cleanup();
1648
1649         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1650
1651         if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
1652                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1653         else if (torture_onoff_failures())
1654                 rcu_torture_print_module_parms(cur_ops,
1655                                                "End of test: RCU_HOTPLUG");
1656         else
1657                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1658         torture_cleanup_end();
1659 }
1660
1661 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
1662 static void rcu_torture_leak_cb(struct rcu_head *rhp)
1663 {
1664 }
1665
1666 static void rcu_torture_err_cb(struct rcu_head *rhp)
1667 {
1668         /*
1669          * This -might- happen due to race conditions, but is unlikely.
1670          * The scenario that leads to this happening is that the
1671          * first of the pair of duplicate callbacks is queued,
1672          * someone else starts a grace period that includes that
1673          * callback, then the second of the pair must wait for the
1674          * next grace period.  Unlikely, but can happen.  If it
1675          * does happen, the debug-objects subsystem won't have splatted.
1676          */
1677         pr_alert("rcutorture: duplicated callback was invoked.\n");
1678 }
1679 #endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1680
1681 /*
1682  * Verify that double-free causes debug-objects to complain, but only
1683  * if CONFIG_DEBUG_OBJECTS_RCU_HEAD=y.  Otherwise, say that the test
1684  * cannot be carried out.
1685  */
1686 static void rcu_test_debug_objects(void)
1687 {
1688 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
1689         struct rcu_head rh1;
1690         struct rcu_head rh2;
1691
1692         init_rcu_head_on_stack(&rh1);
1693         init_rcu_head_on_stack(&rh2);
1694         pr_alert("rcutorture: WARN: Duplicate call_rcu() test starting.\n");
1695
1696         /* Try to queue the rh2 pair of callbacks for the same grace period. */
1697         preempt_disable(); /* Prevent preemption from interrupting test. */
1698         rcu_read_lock(); /* Make it impossible to finish a grace period. */
1699         call_rcu(&rh1, rcu_torture_leak_cb); /* Start grace period. */
1700         local_irq_disable(); /* Make it harder to start a new grace period. */
1701         call_rcu(&rh2, rcu_torture_leak_cb);
1702         call_rcu(&rh2, rcu_torture_err_cb); /* Duplicate callback. */
1703         local_irq_enable();
1704         rcu_read_unlock();
1705         preempt_enable();
1706
1707         /* Wait for them all to get done so we can safely return. */
1708         rcu_barrier();
1709         pr_alert("rcutorture: WARN: Duplicate call_rcu() test complete.\n");
1710         destroy_rcu_head_on_stack(&rh1);
1711         destroy_rcu_head_on_stack(&rh2);
1712 #else /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1713         pr_alert("rcutorture: !CONFIG_DEBUG_OBJECTS_RCU_HEAD, not testing duplicate call_rcu()\n");
1714 #endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1715 }
1716
1717 static int __init
1718 rcu_torture_init(void)
1719 {
1720         int i;
1721         int cpu;
1722         int firsterr = 0;
1723         static struct rcu_torture_ops *torture_ops[] = {
1724                 &rcu_ops, &rcu_bh_ops, &rcu_busted_ops, &srcu_ops, &srcud_ops,
1725                 &sched_ops, &tasks_ops,
1726         };
1727
1728         if (!torture_init_begin(torture_type, verbose))
1729                 return -EBUSY;
1730
1731         /* Process args and tell the world that the torturer is on the job. */
1732         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1733                 cur_ops = torture_ops[i];
1734                 if (strcmp(torture_type, cur_ops->name) == 0)
1735                         break;
1736         }
1737         if (i == ARRAY_SIZE(torture_ops)) {
1738                 pr_alert("rcu-torture: invalid torture type: \"%s\"\n",
1739                          torture_type);
1740                 pr_alert("rcu-torture types:");
1741                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1742                         pr_alert(" %s", torture_ops[i]->name);
1743                 pr_alert("\n");
1744                 firsterr = -EINVAL;
1745                 goto unwind;
1746         }
1747         if (cur_ops->fqs == NULL && fqs_duration != 0) {
1748                 pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
1749                 fqs_duration = 0;
1750         }
1751         if (cur_ops->init)
1752                 cur_ops->init();
1753
1754         if (nreaders >= 0) {
1755                 nrealreaders = nreaders;
1756         } else {
1757                 nrealreaders = num_online_cpus() - 2 - nreaders;
1758                 if (nrealreaders <= 0)
1759                         nrealreaders = 1;
1760         }
1761         rcu_torture_print_module_parms(cur_ops, "Start of test");
1762
1763         /* Set up the freelist. */
1764
1765         INIT_LIST_HEAD(&rcu_torture_freelist);
1766         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1767                 rcu_tortures[i].rtort_mbtest = 0;
1768                 list_add_tail(&rcu_tortures[i].rtort_free,
1769                               &rcu_torture_freelist);
1770         }
1771
1772         /* Initialize the statistics so that each run gets its own numbers. */
1773
1774         rcu_torture_current = NULL;
1775         rcu_torture_current_version = 0;
1776         atomic_set(&n_rcu_torture_alloc, 0);
1777         atomic_set(&n_rcu_torture_alloc_fail, 0);
1778         atomic_set(&n_rcu_torture_free, 0);
1779         atomic_set(&n_rcu_torture_mberror, 0);
1780         atomic_set(&n_rcu_torture_error, 0);
1781         n_rcu_torture_barrier_error = 0;
1782         n_rcu_torture_boost_ktrerror = 0;
1783         n_rcu_torture_boost_rterror = 0;
1784         n_rcu_torture_boost_failure = 0;
1785         n_rcu_torture_boosts = 0;
1786         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1787                 atomic_set(&rcu_torture_wcount[i], 0);
1788         for_each_possible_cpu(cpu) {
1789                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1790                         per_cpu(rcu_torture_count, cpu)[i] = 0;
1791                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
1792                 }
1793         }
1794
1795         /* Start up the kthreads. */
1796
1797         firsterr = torture_create_kthread(rcu_torture_writer, NULL,
1798                                           writer_task);
1799         if (firsterr)
1800                 goto unwind;
1801         if (nfakewriters > 0) {
1802                 fakewriter_tasks = kzalloc(nfakewriters *
1803                                            sizeof(fakewriter_tasks[0]),
1804                                            GFP_KERNEL);
1805                 if (fakewriter_tasks == NULL) {
1806                         VERBOSE_TOROUT_ERRSTRING("out of memory");
1807                         firsterr = -ENOMEM;
1808                         goto unwind;
1809                 }
1810         }
1811         for (i = 0; i < nfakewriters; i++) {
1812                 firsterr = torture_create_kthread(rcu_torture_fakewriter,
1813                                                   NULL, fakewriter_tasks[i]);
1814                 if (firsterr)
1815                         goto unwind;
1816         }
1817         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1818                                GFP_KERNEL);
1819         if (reader_tasks == NULL) {
1820                 VERBOSE_TOROUT_ERRSTRING("out of memory");
1821                 firsterr = -ENOMEM;
1822                 goto unwind;
1823         }
1824         for (i = 0; i < nrealreaders; i++) {
1825                 firsterr = torture_create_kthread(rcu_torture_reader, NULL,
1826                                                   reader_tasks[i]);
1827                 if (firsterr)
1828                         goto unwind;
1829         }
1830         if (stat_interval > 0) {
1831                 firsterr = torture_create_kthread(rcu_torture_stats, NULL,
1832                                                   stats_task);
1833                 if (firsterr)
1834                         goto unwind;
1835         }
1836         if (test_no_idle_hz && shuffle_interval > 0) {
1837                 firsterr = torture_shuffle_init(shuffle_interval * HZ);
1838                 if (firsterr)
1839                         goto unwind;
1840         }
1841         if (stutter < 0)
1842                 stutter = 0;
1843         if (stutter) {
1844                 firsterr = torture_stutter_init(stutter * HZ);
1845                 if (firsterr)
1846                         goto unwind;
1847         }
1848         if (fqs_duration < 0)
1849                 fqs_duration = 0;
1850         if (fqs_duration) {
1851                 /* Create the fqs thread */
1852                 firsterr = torture_create_kthread(rcu_torture_fqs, NULL,
1853                                                   fqs_task);
1854                 if (firsterr)
1855                         goto unwind;
1856         }
1857         if (test_boost_interval < 1)
1858                 test_boost_interval = 1;
1859         if (test_boost_duration < 2)
1860                 test_boost_duration = 2;
1861         if ((test_boost == 1 && cur_ops->can_boost) ||
1862             test_boost == 2) {
1863
1864                 boost_starttime = jiffies + test_boost_interval * HZ;
1865
1866                 firsterr = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "RCU_TORTURE",
1867                                              rcutorture_booster_init,
1868                                              rcutorture_booster_cleanup);
1869                 if (firsterr < 0)
1870                         goto unwind;
1871                 rcutor_hp = firsterr;
1872         }
1873         firsterr = torture_shutdown_init(shutdown_secs, rcu_torture_cleanup);
1874         if (firsterr)
1875                 goto unwind;
1876         firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval * HZ);
1877         if (firsterr)
1878                 goto unwind;
1879         firsterr = rcu_torture_stall_init();
1880         if (firsterr)
1881                 goto unwind;
1882         firsterr = rcu_torture_barrier_init();
1883         if (firsterr)
1884                 goto unwind;
1885         if (object_debug)
1886                 rcu_test_debug_objects();
1887         if (cbflood_n_burst > 0) {
1888                 /* Create the cbflood threads */
1889                 ncbflooders = (num_online_cpus() + 3) / 4;
1890                 cbflood_task = kcalloc(ncbflooders, sizeof(*cbflood_task),
1891                                        GFP_KERNEL);
1892                 if (!cbflood_task) {
1893                         VERBOSE_TOROUT_ERRSTRING("out of memory");
1894                         firsterr = -ENOMEM;
1895                         goto unwind;
1896                 }
1897                 for (i = 0; i < ncbflooders; i++) {
1898                         firsterr = torture_create_kthread(rcu_torture_cbflood,
1899                                                           NULL,
1900                                                           cbflood_task[i]);
1901                         if (firsterr)
1902                                 goto unwind;
1903                 }
1904         }
1905         rcutorture_record_test_transition();
1906         torture_init_end();
1907         return 0;
1908
1909 unwind:
1910         torture_init_end();
1911         rcu_torture_cleanup();
1912         return firsterr;
1913 }
1914
1915 module_init(rcu_torture_init);
1916 module_exit(rcu_torture_cleanup);